The invention relates to an apparatus for assistance for venting a patient.
The invention relates more specifically to an apparatus for assisting with ventilating a patient breathing in successive cycles, each of which comprises a phase of inhalation and a phase of exhalation.
Numerous types of apparatus exist for assisting with ventilation, these also being known as respirators, which make it possible to alleviate respiratory problems by, in particular, giving the patient insufflatory assistance during the inhalation phases.
The patient generally wears on his face a mask which covers his nose and mouth and to which the inhalation circuit is connected so as, in particular, to force the patient""s inhalation.
In order that for it to be useable for various types of disorder, the apparatus for assisting with ventilation has to be able to operate according to different types of ventilation assistance mode, particularly a mode of the volumetric ventilation type, a mode of the percussive ventilation type and a mode of the barometric ventilation type.
In the volumetric-type ventilation assistance mode, the assistance apparatus needs to transmit a constant and/or determined volume of air to the patient. The air flow rate supplied to the patient during the inhalation phase may be constant, decreasing, increasing, sinusoidal, etc.
The value of the flow rate to be transmitted to the patient can vary across a wide range of values which may stretch from 5 to 150 liters per minute. In all cases, it has to be perfectly controlled. In addition, the duration of the increase in flow rate when switching from the patient""s exhalation phase to his inhalation phase, and the time taken for the flow rate to reduce when switching from the patient""s inhalation phase to his exhalation phase needs to be as short as possible.
In the barometric-type ventilation assistance mode, the assistance apparatus needs to transmit gas, particularly a volume of gas, to the patient at a pressure which is constant throughout the patient""s inhalation phase. In this type of ventilation, the pressurized gas flow rate is higher than it is in the volumetric ventilation type of mode. The time taken for the gas pressure to rise needs to be as short as possible. However, ventilation assistance apparatus, particularly ventilation apparatus for use in the home, find it difficult to reduce this time to a minimum.
In the third, percussive ventilation assistance mode, the ventilation assistance apparatus needs to transmit to the patient a gas flow rate which is amplitude-modulated during the various phases of the ventilation. The frequency of the oscillations, which may be between 1 and 10 bursts per second, is difficult to obtain with assistance apparatus of the known type. This is because the inertia of the inhalation valves does not always allow the aforementioned requirements to be met.
In addition, the apparatus for assisting with ventilation requires an electric power supply to allow elements such as the pressurized gas source which may be a bellows or a fanwheel to operate.
Ventilation apparatus, particularly ventilation apparatus for use in the home, does not always allow the use of the aforementioned three modes.
Such apparatus may be used in a hospital environment or at the patients"" home. In either case, it may be used by ambulatory patients, so as not to impede their mobility, and it is then advantageous for them to be offered autonomous apparatus for assisting with ventilation.
In this case, it is necessary to fit the apparatus with batteries that accumulate electric energy. However, the autonomy is greatly limited because of the bulk, weight and cost of such batteries which have to be incorporated into the ventilation assistance apparatus.
In addition, the very diverse range of disorders treated by apparatus for assisting with ventilation means that each apparatus has to be somewhat specialized. Thus, there is a category of disorders that corresponds to each type of apparatus. This reduces the number of pieces of apparatus produced for each category and increases the design and manufacture costs.
With a view to overcoming these drawbacks, the invention proposes an apparatus for assisting with ventilating a patient breathing in successive cycles, each of which comprises a phase of inhalation and a phase of exhalation, of the type comprising:
a pressurized gas source, an outlet orifice of which supplies a stream of pressurized gas intended to be transmitted to the upper airways of the patient;
a pressurized gas stream distribution unit which comprises a transmission circuit which connects the outlet orifice of the gas source to a first free end of a main inhalation pipe, to the second free end of which is fixed a mask, particularly of the face mask type, intended to be worn by the patient; and
an inhalation valve for regulating the said gas stream and which is interposed in the transmission circuit, and is controlled by a control circuit of the apparatus particularly as a function of the values of the flow rate and of the pressure of the gas in the main pipe, characterized in that the inhalation valve is produced in the form of a rotary directional-control valve.
According to other features of the invention:
the inhalation valve for regulating the gas stream comprises a tubular valve body comprising, in its wall, a longitudinal oblong opening which allows the stream of gas from the outlet orifice of the gas source to be transmitted to the first free end of the main inhalation pipe and comprises a spool which is mounted so that it can turn in the body, which is closed at one of its axial ends, and of which an axial end edge, at the opposite end to its closed end, is profiled so that as the spool is turned, the passage cross section of the oblong opening allowing the transmission of the gas stream is varied progressively;
the outlet orifice of the gas source opens into the first free end of a first hole, the second free end of which is plugged by the closed end of the spool and the distribution unit has a recess which opens, on the one hand, opposite the longitudinal oblong opening which it complements, and on the other hand, into a second blind hole to the free end of which the first free end of the main inhalation pipe is fixed;
the spool is turned by a motor, particularly of the stepping type, controlled by the control circuit of the apparatus;
the spool has a device for indexing its angular position;
when the apparatus operates in the volumetric ventilation respiratory assistance mode, during the inhalation phase of which the apparatus has to provide the patient with a predetermined volume of gas, the control circuit of the apparatus controls the angular position of the spool and the pressure supplied by the gas source so that the passage cross section allows the predetermined volume of gas to be transmitted to the patient;
when the apparatus operates in barometric ventilation respiratory assistance mode, during the inhalation phase of which the apparatus has to supply the patient with a gas at a predetermined pressure, the control circuit of the apparatus controls the angular position of the spool so that the passage cross section corresponds to the entirety of the oblong opening and the control circuit of the apparatus controls the pressure supplied by the gas source so that the pressure of the gas in the inhalation pipe is the predetermined gas pressure;
when the apparatus operates in percussive ventilation assistance mode, during the inhalation phase of which the apparatus has to provide the patient with a flow rate which oscillates about a predetermined gas flow rate, the control circuit of the apparatus controls the switching of the angular position of the spool back and forth about a predetermined position that corresponds to the predetermined flow rate and controls the pressure supplied by the gas source;
the pressurized gas source comprises a rotary electric machine controlled in terms of speed by the control circuit, a free end of the rotor of which drives the rotation of a bladed wheel which drives the gas stream through a guide volute of a casing when the rotary electric machine is electrically powered;
the casing has at least one injection point, opening into the volute, for ejecting at least one compressed gas which is supplied by another upstream pressure source, at a second pressure higher than the first pressure, and the compressed gas at the second pressure is capable of driving the rotation of bladed wheel and of the rotor of the rotary electric machine so that the pressurized gas is supplied to the patient at the first pressure and the rotary electric machine acts as an electricity generator and produces electrical energy;
the stream of at least one gas at a second pressure is injected into the casing in a direction more or less tangential to the volute;
the upstream pressure source at least partially consists of a pressurized gas circuit available in a hospital environment;
the source of pressure comprises a pressurized gas reservoir;
the reservoir is incorporated into the apparatus for assisting with ventilation;
the gas at the second pressure is made up at least partially of air;
the compressed gas at the second pressure is made up at least partially of a therapeutic gas;
the therapeutic gas is oxygen;
means for regulating the pressure are inserted between the said other upstream pressure source and injection point;
the apparatus comprises a valve for metering the compressed gas at the second pressure, the opening of which valve is controlled in proportion with the opening of the inhalation valve;
the electrical energy supplied by the rotary electric machine, operating as a generator, at least partially powers the electricity-consuming systems of the apparatus;
the electrical energy produced by the rotary electric machine, operating as a generator, powers and at least partially charges an accumulator battery of the apparatus;
the electrical energy produced by the rotary electric machine is more than the electrical energy consumed by the electricity-consuming systems, so that the apparatus for assisting with respiratory ventilation is autonomous;
the distribution unit comprises controlling means which can order the opening and closing of an exhalation valve which is arranged with equal preference in the inhalation pipe of a single circuit or in the exhalation pipe of a double circuit;
when the apparatus has a double circuit, the exhalation valve is arranged in a module which is fixed to the distribution unit and comprises a pipe for connecting the controlling means to the exhalation valve;
the controlling means allow a positive exhalation pressure to be applied to the exhalation valve, and the positive exhalation pressure is provided by a fan;
the distribution unit comprises measuring means which determine the flow rate of gas flowing, during the exhalation phase, through the inhalation pipe of a single circuit or through the exhalation pipe of a double circuit;
when the apparatus has a double circuit it comprises a module which is fixed to the distribution unit and comprises at least one pipe connecting the measuring means to the exhalation pipe.